Gel Electrophoresis: A Comprehensive Guide for Biotechnology Students

Question 1

In gel electrophoresis, which factors affect how quickly DNA fragments move?

Accepted Answer

Size of DNA fragments

Accepted Answer

Concentration of agarose gel

Accepted Answer

Voltage applied

Answer

Temperature of the gel

Question 2

In agarose gel electrophoresis, which factor determines the size of DNA fragments that can be separated?

Accepted Answer

Agarose concentration

Answer

Gel thickness

Answer

Voltage applied

Answer

Gel temperature

Question 3

In gel electrophoresis, what factor primarily determines the speed at which DNA fragments move through the gel?

Accepted Answer

Size of DNA fragments

Answer

Concentration of DNA fragments

Answer

Percentage of agarose in the gel

Answer

Voltage applied during electrophoresis

Question 4

Which of the following best describes the primary purpose of gel electrophoresis?

Accepted Answer

To separate and analyze DNA fragments based on their size and charge

Answer

To amplify DNA fragments

Answer

To purify DNA samples

Question 5

What is the primary role of the DNA ladder in gel electrophoresis?

Accepted Answer

To provide a reference for estimating the size of unknown DNA fragments

Answer

To prevent DNA fragments from migrating

Answer

To stain DNA fragments for visualization

Question 6

Which of the following factors does NOT affect the rate of migration of DNA fragments in gel electrophoresis?

Accepted Answer

DNA concentration

Answer

DNA fragment length

Answer

Agarose gel concentration

Answer

Electric field strength

Question 7

What type of staining is specifically used to visualize DNA fragments in gel electrophoresis, emitting a distinctive orange fluorescence?

Accepted Answer

Ethidium bromide staining

Answer

Crystal violet staining

Answer

Methylene blue staining

Answer

Congo red staining

Question 8

Which of the following is a key advantage of gel electrophoresis compared to some other DNA separation techniques?

Accepted Answer

Provides high-resolution separation of DNA fragments, allowing for precise size determination

Answer

Significantly faster and less time-consuming

Answer

More cost-effective and requires less specialized equipment

Question 9

Gel electrophoresis separates DNA fragments based on which fundamental principles?

Accepted Answer

Differences in size, charge, and shape of DNA molecules

Answer

DNA fragments are attracted to oppositely charged electrodes

Question 10

In forensic science, gel electrophoresis is widely used in which specific application?

Accepted Answer

DNA fingerprinting, a technique for identifying individuals based on their unique DNA profiles

Answer

Mutation detection

Answer

Genetic sequencing

Answer

Gene expression analysis

Question 11

Which of the following is NOT a necessary component for gel electrophoresis setup?

Accepted Answer

Petri dish

Answer

Agarose gel

Answer

Electrophoresis buffer

Answer

Power supply

Question 12

What is the primary role of agarose in gel electrophoresis?

Accepted Answer

To create a matrix for DNA separation

Answer

To stain the DNA bands

Answer

To neutralize the DNA fragments

Answer

To provide electrical conductivity

Question 13

Which of the following statements about electrophoresis buffer is correct?

Accepted Answer

It contains ions to facilitate current flow

Answer

It is used to dissolve the DNA samples

Answer

It is added after the gel has solidified

Answer

It is always acidic

Question 14

Which dye is most commonly used to visualize DNA bands on an agarose gel?

Accepted Answer

Ethidium bromide

Answer

Acridine orange

Answer

Methylene blue

Answer

Bromophenol blue

Question 15

Which of the following applications of gel electrophoresis is NOT related to DNA analysis?

Accepted Answer

Protein purification

Answer

DNA fingerprinting

Answer

DNA fragment sizing

Answer

DNA sequencing

Question 16

What is the fundamental principle behind the separation of DNA fragments during gel electrophoresis?

Accepted Answer

Migration of negatively charged DNA towards the positive electrode

Answer

Interaction of DNA with the agarose gel matrix

Answer

Denaturation and renaturation of DNA strands

Answer

Size-dependent diffusion of DNA fragments

Question 17

Which of the following factors directly influences the migration rate of DNA fragments during gel electrophoresis?

Accepted Answer

The size of the DNA fragments

Answer

The type of electrophoresis apparatus used

Answer

The concentration of agarose in the gel

Answer

The amount of ethidium bromide in the gel

Question 18

The purpose of ethidium bromide in gel electrophoresis is to:

Accepted Answer

Visualize DNA fragments under ultraviolet light

Answer

Prevent DNA degradation during electrophoresis

Answer

Enhance the binding of DNA to the agarose gel

Question 19

In an agarose gel, which DNA sample would migrate further: one with fragments of 500 base pairs (bp) or one with fragments of 1000 bp?

Accepted Answer

Sample with 500 bp fragments

Answer

Sample with 1000 bp fragments

Answer

Both samples would migrate the same distance

Question 20

Which type of electrophoresis is specifically designed for the separation of proteins?

Accepted Answer

Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE)

Answer

Agarose gel electrophoresis

Answer

Capillary electrophoresis

Answer

Pulsed-field gel electrophoresis

Question 21

A scientist conducting gel electrophoresis to analyze a DNA sample containing a specific gene expects to observe a band at approximately 500 bp. However, they only observe a band at 250 bp. What could be a possible explanation?

Accepted Answer

The gene was likely cut into smaller fragments by a restriction enzyme during the experiment

Answer

The electrophoresis was run at too high a voltage

Answer

The DNA sample was degraded during preparation

Question 22

What is the primary purpose of a loading dye in gel electrophoresis?

Accepted Answer

To visualize the DNA sample during loading and monitor the electrophoresis progress

Answer

To enhance the migration of DNA fragments through the gel

Answer

To prevent DNA degradation during electrophoresis

Question 23

Which of the following is NOT an application of gel electrophoresis?

Accepted Answer

Gene therapy

Answer

Genetic testing for inherited diseases

Answer

Paternity testing

Answer

DNA fingerprinting

Question 24

What is the primary function of a molecular weight marker in gel electrophoresis?

Accepted Answer

To provide a reference for estimating the size of unknown DNA fragments

Answer

To improve the resolution of DNA bands

Answer

To enhance the staining of DNA fragments

Question 25

Which buffer system is commonly used in agarose gel electrophoresis?

Accepted Answer

TAE (Tris-acetate-EDTA) or TBE (Tris-borate-EDTA)

Answer

MES (2-(N-morpholino)ethanesulfonic acid)

Answer

Acetate buffer

Answer

Sodium phosphate buffer

Question 26

What is the main function of loading dye in gel electrophoresis?

Accepted Answer

To visualize DNA fragments and aid in sample loading

Answer

To stain DNA fragments

Answer

To increase the conductivity of the gel

Answer

To prevent DNA degradation

Question 27

What is the primary purpose of agarose in gel electrophoresis?

Accepted Answer

To establish a matrix for separating DNA fragments

Answer

To facilitate sample loading

Answer

To stain DNA fragments

Answer

To provide electrical conductivity

Question 28

The principle of gel electrophoresis involves separating DNA fragments based on which characteristic?

Accepted Answer

Size and electrical charge

Answer

Shape and density

Answer

Sequence and base composition

Question 29

Which of the following is a common application of gel electrophoresis in biotechnology?

Accepted Answer

DNA fingerprinting

Answer

Cell culture

Answer

Microscopy

Answer

Protein purification

Question 30

What effect does increasing the concentration of agarose have on the separation of DNA fragments?

Accepted Answer

Enhances separation and resolution of smaller DNA fragments

Answer

No significant impact on DNA separation

Answer

Reduces the overall separation of DNA fragments

Answer

Increases migration speed of larger DNA fragments

Question 31

Which of the following factors DOES NOT affect the migration rate of DNA fragments during gel electrophoresis?

Accepted Answer

Concentration of the agarose gel

Answer

Presence of ethidium bromide in the gel

Answer

Voltage applied across the gel

Answer

Size of the DNA fragments

Question 32

What is the primary function of the loading buffer used in gel electrophoresis?

Accepted Answer

To add density and tracking dye to the samples

Answer

To increase the viscosity of the buffer

Answer

To neutralize the charge of the DNA fragments

Answer

To denature the DNA molecules

Question 33

What is the purpose of using ethidium bromide in gel electrophoresis?

Accepted Answer

To visualize DNA fragments under UV light

Answer

To denature the DNA molecules

Answer

To increase the conductivity of the gel

Answer

To prevent DNA degradation during electrophoresis

Question 34

You are analyzing a DNA sample with two restriction enzymes that produce fragments of 200 bp and 300 bp. What would you expect to see on the gel after electrophoresis?

Accepted Answer

Three bands: one at 200 bp, one at 300 bp, and one at 500 bp

Answer

Two bands: one at 200 bp and one at 300 bp

Answer

One band at 500 bp

Question 35

What is the main advantage of using a higher concentration of agarose gel in electrophoresis?

Accepted Answer

Improved resolution of smaller DNA fragments

Answer

Faster migration of DNA fragments

Answer

Increased sensitivity of DNA detection

Answer

Reduced risk of DNA degradation

Question 36

What is the purpose of running a DNA ladder in gel electrophoresis?

Accepted Answer

To determine the size of the DNA fragments in the sample

Answer

To stabilize the gel during electrophoresis

Answer

To increase the conductivity of the gel

Question 37

Which of the following is NOT a common application of gel electrophoresis?

Accepted Answer

Analyzing protein structure

Answer

Comparing DNA profiles from different individuals

Answer

Identifying mutations in genes

Answer

Analyzing the size of DNA fragments after restriction enzyme digestion

Question 38

Why is it important to carefully prepare the agarose gel before running electrophoresis?

Accepted Answer

To ensure consistent migration of DNA fragments and accurate analysis

Answer

To prevent the gel from melting during electrophoresis

Answer

To improve the conductivity of the gel

Question 39

You are analyzing a DNA sample with two restriction enzymes that produce fragments of 100 bp, 200 bp, and 300 bp. However, you only see two bands on the gel after electrophoresis: one at 100 bp and another at 300 bp. What is the most likely explanation for this result?

Accepted Answer

The 200 bp fragment was not generated by the restriction enzymes

Answer

The 200 bp fragment was degraded during electrophoresis

Answer

The 200 bp fragment did not migrate into the gel

Question 40

You are running a gel electrophoresis experiment with DNA fragments of sizes 100 bp, 500 bp, and 1000 bp. What order would you expect to see them in the gel (from anode to cathode)?

Accepted Answer

1000 bp, 500 bp, 100 bp

Answer

100 bp, 500 bp, 1000 bp

Answer

500 bp, 100 bp, 1000 bp